Fever alarm system

ABSTRACT

A body temperature measurement device includes a unit ( 2 ) that continually measures body temperature and transmits the measurement through an RF transmitter ( 14 ) to a display unit ( 30 ). The display unit ( 30 ) includes an RF receiver ( 37 ), a processor ( 33 ), and a display ( 35 ) that shows the temperature. The display unit ( 30 ) includes an adjustable threshold alarm circuit that turns on an alarm whenever the temperature rises above a defined threshold.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a clinical thermometer, and moreparticularly to a skin thermometer, which performs calculation of oralor rectal temperature. The thermometer is connected to an RFtransmitter/receiver system to display the temperature in a remote placeand to raise an alarm when the temperature is above a predeterminedthreshold.

2. Description of the Related Art

Numerous devices for body temperature measurement are known. Somedevices measure temperature continuously. U.S. Pat. Nos. 4,509,533,4,333,477, 4,232,684, 4,030,483 describe skin fever thermometers, butthe disclosed thermometers use liquid crystal which changes coloraccording to temperature range. The prior art does not suggest a methodfor accurate reading and calculation of body (oral and rectal)temperature. The prior art also does not provide a solution for remotereading and remote alarm system when the fever rises above a certainthreshold.

SUMMARY OF THE INVENTION

It is the first objective of this invention to provide a solution foraccurate, continuous measurement of skin temperature and to accuratelycalculate body temperature. The temperature measurement devicepreferably comprises two thermistors. The first thermistor is attachedto the skin and is thermally isolated from the surroundings. The otherthermistor is thermally isolated from the skin and measures the roomambient temperature. A look-up correlation table in the processorcorrelates the temperature readings to oral or rectal temperature whiletaking into consideration the room temperature.

Another objective of this invention is to provide a remote reading ofthe temperature through a wireless communication link and to sound oractivate an alarm whenever the temperature rises above a predeterminedthreshold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing of the wrist temperature measurement device of thepreferred embodiment.

FIG. 2 is a schematic electronic drawing of the measurement unit of thepreferred embodiment.

FIG. 3 is a schematic electronic drawing of the intermediate unit of thepreferred embodiment.

FIG. 4 is a schematic electronic drawing of the remote display andmonitoring unit of the preferred embodiment.

FIG. 5 illustrates a method for calculating body temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates the general construction of the part of the skintemperature measurement device attached to the body. According to thepreferred embodiment, this unit 2 has the shape of the wrist and is madeof a soft material with a very low thermal conductivity, such as foamedpolyurethane. The unit incorporates a flexible electronic board 1 with aconnector 7 that turns the unit on when it closes. Two thermistors 3, 5are assembled on the electronic board. The thermistor 3 faces the skinside and is attached to the skin while being thermally isolated from theambient room temperature by the polyurethane. The thermistor 5 facesaway from the wrist and is thermally isolated from the skin in order tomeasure the immediate ambient temperature surrounding the skin. Theflexible printed board 1 also has an RF antenna printed on the boarditself. A soft disposable pad can be attached to the inner side of theunit in order to keep the unit hygienically clean.

FIG. 2 shows a schematic circuit diagram of the electronic unit 19 ofthe device attached to the skin. A microprocessor or processing unit 10preferably includes two resistance-to-frequency converters, such asseries 6200 made by Epson, Japan. The two thermistors 12 and 13, whichrespectively correspond to the thermistors 3 and 5, are preferablydirectly connected to the microprocessor. The thermistor 12 measures theskin temperature continuously and is thermally isolated from thesurrounding ambient temperature. The thermistor 13 continuously measuresthe ambient surrounding temperature and is thermally isolated from theskin. The microprocessor 10 continuously reads the values of thethermistors and calculates oral or rectal body temperature, taking intoconsideration the skin temperature and the temperature of the ambientsurroundings. There is typically a delay between the change of theambient temperature and the sensing of this change by the thermistor 12due to the isolation of the thermistor 12 from the ambient temperatureand the thermal mass of the device. The length of this delay has beenmeasured and can be up to 30 minutes. In order to improve measurementaccuracy, the microprocessor stores the ambient temperature changesmeasured by thermistor 13 and takes into consideration the changes ofambient temperature, or in other words, the history of the ambienttemperature measurements, while calculating the body temperature. AnEEPROM 17 contains look-up tables taken out of experimental data of bodytemperature versus skin temperature, ambient temperature and changes ofambient temperature over time. The microprocessor 10 uses the look-uptables in calculating body temperature based upon the measuredparameters. A method for calculating body temperature is illustrated inFIG. 5. The calculated body temperature is transmitted through atransmitter 14 (FIG. 2) and a printed antenna 15, to a remote circuit.The unit is powered by a battery 16, which is preferably a lithiumbattery that has a stable voltage and a long life. The battery powersupply is connected to the circuit through connector 18.

FIG. 3 is a schematic electronic diagram of an intermediatetransmitter/receiver unit 28 incorporated in the apparatus according tothe preferred embodiment. The intermediate unit 28 is preferably placedclose to the subject whose temperature is to be measured. Theintermediate unit is used in order to save power of the measurementunit, which transmits the data to the intermediate unit. The datatransmitted from the skin temperature measurement unit (shown in FIG. 2)is received through an antenna 26 and a receiver 20. The receiver 20 isconnected through a buffer 21 to a transmitter 22 and an antenna 23 thattransmit the data to a display and a monitoring unit (shown in FIG. 4).The intermediate unit 28 may also include a microphone 25 and anamplifier 24 to collect and transmit vocal data, in which case thesystem can also operate as a “Baby Monitor.” All the electroniccomponents such as the receiver 20, the buffer 21, the transmitter 22,the amplifier 24 and the microphone 25 are standard electroniccomponents used for baby monitoring devices and are known to personsskilled in the art.

FIG. 4 shows the electronic schematic diagram of the display andmonitoring unit 30. The unit 30 receives body temperature data and vocaldata from the intermediate unit (shown in FIG. 3) through an antenna 31and a receiver 37. The receiver 37 is connected to a microprocessor 33through a buffer 32. The microprocessor 33 processes the data anddisplays the temperature on the liquid crystal display (LCD) 35 and alsoactivates the speaker 36 in case of vocal data. Two momentarypush-buttons 34 are connected to the microprocessor 33 to adjust therequired temperature level for an alarm. When the temperaturemeasurement is above the alarm level, an alarm will sound through thespeaker 36. The LCD 35 preferably continuously displays the subject'stemperature and the alarm threshold level.

In one alternative embodiment, the microprocessor or processing unit 10that calculates temperature can be incorporated into either theintermediate transmitter/receiver unit 28 or the monitoring unit 30. Thetransmitter 14 in this case can transmit raw data obtained from thesensors 12 and 13.

In one alternative embodiment, the transmitter 14 can be configured totransmit data directly to the monitoring unit 30. In this case, theintermediate unit 28 is not necessary.

Although the invention has been described in terms of certain preferredembodiments, other embodiments that are apparent to those of ordinaryskill in the art, including embodiments which do not provide all of thefeatures and advantages set forth herein, are also within the scope ofthis invention. Accordingly, the scope of the invention is defined bythe claims that follow.

What is claimed is:
 1. A temperature measurement apparatus comprising: afirst temperature sensor configured to provide a signal related to skintemperature; a second temperature sensor configured to provide a signalrelated to ambient room temperature; an insulating barrier disposedbetween the first temperature sensor and the second temperature sensor;a processing unit in communication with the first and second temperaturesensors, the processing unit configured to calculate body temperaturebased at least upon signals provided by the first and second temperaturesensors; and a flexible printed circuit board, wherein the processingunit is disposed on the printed circuit board.
 2. The apparatus of claim1, wherein the first temperature sensor and the second temperaturesensor are disposed on the printed circuit board.
 3. The apparatus ofclaim 1, wherein the printed circuit board is embedded within theinsulating barrier.
 4. The apparatus of claim 1, wherein the processingunit is configured to store a plurality of readings from the secondtemperature sensor.
 5. The apparatus of claim 1, wherein the processingunit is further configured to calculate the body temperature based atleast upon a reading from the first temperature sensor and upon areading from the second temperature sensor obtained before the readingfrom the first temperature sensor.
 6. The apparatus of claim 1, whereinthe processing unit is configured to calculate body temperature by atleast referencing empirical data stored in a lookup table.
 7. Theapparatus of claim 1, wherein the body temperature is oral temperature.8. The apparatus of claim 1, wherein the body temperature is rectaltemperature.
 9. The apparatus of claim 1, wherein the first temperaturesensor and the second temperature sensor are thermistors.
 10. Theapparatus of claim 1, further comprising: a transmitter configured totransmit temperature data; and a monitoring unit configured to receivethe temperature data and to display body temperature, wherein the bodytemperature is related to the temperature data.
 11. The apparatus ofclaim 10, wherein the temperature data is the body temperature.
 12. Theapparatus of claim 10, wherein the transmitter is configured to transmitthe temperature data directly to the monitoring unit.
 13. The apparatusof claim 11, further comprising an antenna printed on the flexiblecircuit board.
 14. The apparatus of claim 11, wherein the processingunit is disposed in the monitoring unit.
 15. A temperature measurementapparatus comprising: a first temperature sensor configured to provide asignal related to skin temperature; a second temperature sensorconfigured to provide a signal related to ambient room temperature; aninsulating barrier disposed between the first temperature sensor and thesecond temperature sensor; a processing unit in communication with thefirst and second temperature sensors, the processing unit configured tocalculate body temperature based at least upon signals provided by thefirst and second temperature sensors; a transmitter configured totransmit temperature data; a monitoring unit configured to receive thetemperature data and to display body temperature, wherein the bodytemperature is related to the temperature data; and an intermediatereceiving and transmitting unit configured to receive the temperaturedata transmitted by the transmitter and to retransmit the temperaturedata to the monitoring unit.
 16. The apparatus of claim 15, wherein theprocessing unit is disposed in the intermediate receiving andtransmitting unit.
 17. The apparatus of claim 15, wherein theintermediate receiving and transmitting unit comprises a microphone, andwherein the intermediate receiving and transmitting unit is configuredto transmit audio signals captured by the microphone to the monitoringunit.
 18. The apparatus of claim 17, wherein the monitoring unitcomprises a speaker, and wherein the monitoring unit is configured toreproduce, through the speaker, audio signals received from theintermediate receiving and transmitting unit.